1. Field of the Invention
The present invention generally relates to systems and methods for cooling and climate control of an offshore wind turbine, and more particularly to systems and methods to cool the air inside the nacelle and the heat generating components of an offshore wind turbine, such as the drivetrain, the electrical generator, the converter, and the transformer. It is noted that although the wind turbine cooling and climate control system of the present invention is preferably directed to an offshore installation, it can also be used in an onshore installation.
2. Related Art
A wind turbine converts the kinetic energy of the wind into electrical energy through its rotor, drivetrain, electrical generator, and converter. An electrical transformer converts the low voltage output from the converter into a high voltage output before the output is sent to the substation at the wind farm. The wind turbine nacelle houses these mechanical and electrical components, namely, the drivetrain, the electrical generator, the converter and the transformer (usually located in the nacelle to reduce the power loss due to low voltage electrical transmission). The nacelle also houses the components of the hydraulic system needed for blade pitching and nacelle yawing.
These components generate a significant amount of heat while the wind turbine is operating. For their protection and their efficient operation, the heat generated by these components has to be continuously removed. This is typically done by circulating a coolant such as a mixture of ethylene glycol and water through the heat exchangers built into these components. The coolant then transports the heat from these components and dissipates it to the ambient air with the help of air-cooled radiators mounted on the outside of the nacelle.
In addition to dissipating heat to the coolant, the heat generating components of the wind turbine also dissipate a significant amount of heat from their outer surfaces to the air inside the nacelle. Moreover, components such as the transformer dissipate the heat primarily to the surrounding air. Thus, the air inside the nacelle needs to be either continuously replaced by fresh cooler air (an open airflow system) or cooled and re-circulated (a closed airflow system).
In a wind turbine with an open airflow system, the cooler ambient air usually enters through one or more inlets at the nacelle bottom and flows through the nacelle, thus removing heat from the outer surfaces of the heat generating components. The warmer air exits the nacelle to the outside through one or more outlets at the nacelle top. The fans, typically located either at the inlets or the outlets, and other airflow control devices such as vanes help regulate the airflow through the nacelle and, thus, over the heat generating components.
In a turbine with a closed airflow system, the warmer air inside the nacelle is transported to outside the nacelle or to the tower bottom and cooled through a chiller or through an air-to-air heat exchanger and the cooler air is re-circulated through the nacelle. Fans or blowers and other flow control devices help circulate and regulate the airflow through the nacelle.
Thus, the wind turbine climate control system (a general term that refers to all the components associated with the airflow and maintaining the air temperature) helps cool the heat generating components of the turbine by regulating the nacelle air temperature. An open airflow system is typically more economical and simpler to use than a closed airflow system, and, therefore, it is generally used in onshore wind turbines.